The clinically proven components of whole blood include, e.g., red blood cells, which can be used to treat chronic anemia; plasma, which can be used as a blood volume expander or which can be fractionated to obtain Clotting Factor VIII-rich cryoprecipitate for treatment of hemophilia; and concentrations of platelets, used to control thrombocytopenic bleeding.
Along with the growing demand for these blood components, there is also a growing expectation for purity of the blood product. Before storing blood components such as red blood cells or platelets for later transfusion, it is believed to be desirable to minimize the presence of impurities or other materials that may cause undesired side effects in the recipient.
For example, it is generally considered desirable to remove leukocytes from such blood components before storage, or at least before transfusion. It is also believed beneficial that potential blood-born pathogens, e.g., free viruses and bacteria, be inactivated from blood components prior to transfusion, e.g., through the use of photoactive and non-photoactive chemical reactions.